Finding the Fourth Proportional to 105.24, 145.06 and 86.78

Step by Step Solution

1. Step 1: Write the proportion equation
   105.24 : 145.06 = 86.78 : x
2. Step 2: Convert to fraction form
   105.24/145.06 = 86.78/x
3. Step 3: Cross multiply
   105.24x = 145.06 × 86.78
4. Step 4: Simplify right side
   105.24x = 12,588.31
5. Step 5: Solve for x
   x = 12,588.31/105.24
6. Step 6: Final answer
   x = 119.62